Difference between revisions of "Corynebacterium species"

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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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#REDIRECT[[:Category:Corynebacterium species]]
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===Overview===
 
 
 
*Common inhabitants of skin and mucous membranes of animals
 
*Opportunistic infections
 
*Cause pyogenic infections
 
*Most species host specific
 
 
 
 
 
===Characteristics===
 
 
 
*Small, tough, Gram positive rods
 
*Pleomorphic
 
*Cluster together to resemble Chinese characters - coryneform morphology
 
*Known as diphtheroids
 
*Catalase positive, oxidase negative
 
*Facultative anaerobes
 
*Require enriched media for growth
 
*Non-motile
 
 
 
 
 
===Pathogenesis and pathogenicity===
 
 
 
*Pyogenic causing suppurative infections except for ''C. bovis''
 
*''C. pseudotuberculosis'':
 
**Facultative intracellular pathogen inside macrophages
 
**Cell wall lipid
 
**Produces a phospholipase toxin which hydolyses sphingomyelin in mammalian cell membranes
 
**Phospholipase may enhance survival and multiplication in host in early stages
 
*''C. renale''
 
**Urinary tract pathogens
 
**Produce urease and hydrolyse urea
 
**Possess fimbriae for attachment to urogenital mucosa
 
**Infection when immunity reduced or following tissue damage during parturition
 
 
 
 
 
===''Corynebacterium pseudotuberculosis''===
 
 
 
*Caseous lymphadenitis:
 
**''C. pseudotuberculosis'' carried on skin of sheep
 
**Non-nitrate-reducing biotype
 
**Infection follows tissue trauma such as shearing wounds
 
**Incubation period 3 months
 
**Chronic suppurative infection of sheep, goats and occasionally cattle
 
**Abscessation of superficial and internal lymph nodes if haemtogenous spread occurs
 
**Caseous abscesses with green colour and onion ring appearance
 
**Ill thrift and pneumonia may occur
 
**Condemnation of carcasses and hides
 
**Infection spread by pus from abscesses, and oculonasal secretions
 
**Organism survives in environment for several months
 
**Sandwich ELISA detects circulating antibodies to phospholipase toxin
 
**Control: importation measures including screening; culling of infected sheep, stict hygiene; inactivated vaccine
 
*Ulcerative lymphangitis:
 
**Nitrate reducing biotype
 
**Disease in horses and cattle
 
**Infection through skin wounds
 
**Lymphangitis of lower limbs or abscessation in pectoral region
 
**Slow onset, usually becomes chronic
 
**Affected lymphatic vessels swollen and firm with nodules
 
**Oedema in affected limbs
 
**Ulcerative nodules exude thick green pus
 
**Lymphangitis and lymphadenitis in cattle with abscesses as well as coronary band lesions causing lameness
 
**Antibiotic treatment and topical iodophore shampoo
 
*May cause [[Muscles - inflammatory#Abscesses|myositis]]
 
*Involved in [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]]
 
 
 
 
 
===''Corynebacterium renale''===
 
 
 
*''C. renale, C. pilosum, C. cystitidis''
 
*Found in the vulva, vagina and prepuce of normal cattle
 
*Bovine pyelonephritis
 
**Stress of parturition and short urethra predisposes cows to urinary tract infection
 
**Cystitis especially with ''C. cystitidis
 
**Ascending infection from bladder through ureters causes pyelonephritis
 
**Fever, anoexia, decreased milk production
 
**Restlessness; kicking of abdomen indicate renal pain
 
**Dysurea, arched back, bloody urine
 
**Chronic infection causes extensive renal damage
 
**Enlarged ureters and kidneys palpated per rectum
 
**Culture from urine; protein and red blood cells in urine
 
**Antibiotics e.g. penicillin for at least three weeks
 
*Ulcerative balanoposthitis (pizzle rot):
 
**Common in Merino sheep and Angora goats
 
**Ulceration around prepucial orifice with brown crust, and occasionally on vulva of ewes
 
**Bacteria hydrolyse urea to ammonia which causes mucosal irritation and ulceration
 
**High urine urea level, from high protein intake may predispose to condition
 
**High oestrogen levels in pastures also predisposes
 
**Castration and heavy wool aroung the prepuce are risk factors
 
 
 
 
 
===''Corynebacterium bovis''===
 
 
 
*Subclinical mastitis in cattle
 
*Found in teat cistern
 
*Causes mild neutrophil response in teat canal of healthy dairy cows and may protect against invasion from more pathogenic bacteria
 
 
 
 
 
===Diagnosis===
 
 
 
*Samples include pus, exudate, affected tissues and urine
 
*Presence of coryneform organisms in smears
 
*Culture on blood agar, selective blood agar and MacConkey agar
 
*Do not grow on MacConkey
 
*Colony characteristics:
 
**''C. bovis'': lipophilic bacterium; small, white, dry, non-haemolytic colonies on plates inoculated with bovine milk
 
**''C. kutscheri'': white colonies; occasionally haemolytic
 
**''C. pseudotuberculosis'': small, white coloniess surrounded by narrow zone of complete haemolysis; colonies become dry and cream-coloured
 
**''C. renale'': small, non-haemolytic colonies after 24 hours; pigment produced after 48 hours
 
*Biochemical reactions:
 
**Certain strains of ''C. pseudotuberculosis'' reduce nitrates
 
**All pathogenic strains except ''C. bovis'' produce urease
 
*Enhancement of haemolysis produced by ''C. pseudotuberculosis'' when inoculated across a streak of ''Rhodococcus equi''
 

Latest revision as of 12:30, 12 May 2010